1. Field of the Invention
This invention relates to soft-sided luggage frames and a method of manufacturing such frames.
2. Description of Related Art
Existing soft-sided luggage frames are made of steel, aluminum, plastic extrusions or combinations thereof, the components of which must be individually manufactured for one frame at a time. Most such frames comprise multiple independent components which must be assembled. Manufacturing of the components and the assembly substantially increases the manufacturing cost.
An example of a soft-side luggage frame is presented in Bradley et al., U.S. Pat. No. 4,418,804, where the frame includes a plastic element defining the bottom and bottom corners and an aluminum element secured to the bottom element in defining the top and sides of the frame.
One-piece soft-side frames are known, such as the injection molded plastic frame sold by Delsey Luggage, Inc. and identified as the Helium frame. This frame has the disadvantage of being very costly because of the costs of the high strength precision tooling for injection molding. Wood and cardboard frames are also known but are subject to breakage and cannot be adapted to receive handles, locks, wheels and other accessories.
Those soft-side suitcase frames which are made of the same materials at the sides and top, such as that in Bradley et al. and the Delsey Helium frame, must compromise between the flexibility needed to recover from shocks and pressure and the rigidity needed to support the shape of the luggage at the top and bottom when the case is carried under a load or is rolled when equipped with wheels. Pelavin et al., U.S. Pat. No. 4,004,664, teaches a frame construction using the same material throughout but which includes articulated metal plates and springs to allow shock and pressure recovery flexibility. The structure of the device in Pelavin et al. is expensive and labor intensive to manufacture.
A particular difficulty of soft-side luggage frames is the necessity to provide a smooth rim which will give shape to the corners and around which the opening may be easily zipped shut. If the soft exterior of the case is snugly fitted to a full width frame, the zipper will catch on the edge of the frame. Where frames are not full width, the corners are supported most often with a separate corner reinforcement of flexible plastic as taught in Bradley et al., but even this solution results in resistance to the closing of the zipper.
The subject invention overcomes the disadvantages of the prior art by providing an economical method of manufacturing soft-sided luggage frames and by providing a frame having the required rigidity and the needed flexibility.